As you may have noticed at your last high school reunion, some people age more gracefully than others. Jean Calment, who died in 1997 at the age of 122 and is the world record holder for longest human lifespan, is reported to have stayed mentally sharp her entire life. She took up fencing at 85 and rode a bike until she was 100. At the other extreme, people with early-onset Alzheimer’s may begin experiencing cognitive deficits in their 30s.
People also differ in subjective age—how old they feel. Older adults who report feeling younger than their years tend to be mentally and physically healthier than people who report feeling older. According to one popular view, aging is a “state of mind” that is directly under a person’s control. However, a new study published in the journal Intelligence reveals that the developmental processes that influence subjective age actually begin early in life. People who scored high on an IQ test in their late teens felt younger once they reached their 70s than people who scored lower on the IQ test.
The data were from the Wisconsin Longitudinal Study (or WLS), which has followed a random sample of 10,317 people born between 1937 and 1940. The participants took an intelligence test in 1957, when they were seniors in high school, while data on education, health and personality were collected in the early 1990s. Then, in 2011, the participants were asked how old they felt most of the time. For each person, the researchers computed an index of subjective age by subtracting this value (“felt age”) from chronological age and dividing the difference by chronological age. Thus, people with a negative score felt older than they actually were, whereas people with a positive score felt younger.
On average, the people in the study felt 17 percent younger than their chronological age. For example, a person who was 70 years old reported feeling like they were only 58. However, the difference between chronological age and subjective age varied by intelligence, as assessed by the IQ test given more than 50 years earlier. The people with the highest IQs reported feeling the youngest.
IQ correlates with any number of factors that could explain this correlation, including education. People who score high on intelligence tests are generally more educated than people who score lower. (The correlation between IQ and educational achievement is among the highest correlations observed in psychological research.) In turn, highly educated people secure better paying and less physically strenuous jobs than less educated people and can afford things that might keep them feeling young, from good healthcare to luxury vacations.
As plausible as this explanation seems, statistical analyses revealed that the relationship between IQ and subjective age was explained not by education but by a personality trait: openness to experience. A person high in openness to experience is intellectually curious, independent and imaginative; they prefer variety over routine and enjoy learning and trying new things. Once the researchers statistically controlled for openness to experience, the relationship between IQ and subjective age vanished.
The study helps us understand the relationship between psychological traits measured early life and the aging process. As now documented in large-sample studies from around the world, intelligence predicts longevity: People with high IQs tend to live longer than people with lower IQs. One reason this may be the case is that intelligence tests, in addition to measuring cognitive functioning that bears on people’s ability to make decisions conducive to living a long and healthy life, may capture information about people’s personalities. People who are high in openness to experience may be more likely to seek out information that can be beneficial to their health. Staying abreast of changes in the world, they may also feel more vital than people lower in openness to experience.
The study also opens avenues of applied research on aging. Both intelligence and personality are relatively stable psychological traits and are not easily changed through intervention. However, interventions that target specific behaviors such as exercising, eating healthy, and becoming civically engaged can improve people’s physical and psychological well-being. One possible consequence of these interventions is that people may begin to feel younger than their years. There may be no fountain of youth, but this type of intervention may at least soften people’s experience of growing older.